Why didnt you boys tell me that 93 and a 5.0 is a match made in heaven!!!!!!!!! LOL
Every since I started driving I have always been cheap with gas and always use 87 sometimes 89.
I ran my Stang with 93 and it is NIGHT AND DAY!!!!!! The car purrrrrrrrssssss!!!! Shifts better & everything. Cant wait to finish my engine HCI mods. When fiirst shopping I was looking for a New edge body. But I have always been a 5.0 guy. This car is starting to win me all the way over. Anyways, just thinking out loud.

SN Certified Technician

You are equating quality with price based on the marketing hype. Higher octane fuel isn't "better" it's "different". The difference is in the rate at which it burns. Higher octane fuels just burn slower. Does your car need higher octane fuel? Perhaps, if you have increased the compression ratio, are boosted and are pushing the limits on the timing advance. An otherwise basic stock 5.0 should run great on 87 octane. If it doesn't, there is likely an underlying cause that needs to be addressed.

I beg to differ. I dont know exactly what the 93 gas is doing. But the car runs much better. It has better pick up the trans shifts better. Car feels stronger. I went back to 87 to test it. HUGE difference.

You are equating quality with price based on the marketing hype. Higher octane fuel isn't "better" it's "different". The difference is in the rate rate at which it burns. Higher octane fuels just burn slower. Does your car need higher octane fuel? Perhaps, if you have increased the compression ratio, are boosted and are pushing the limits on the timing advance. An otherwise basic stock 5.0 should run great on 87 octane. If it doesn't, there is likely an underlying cause that needs to be addressed.

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If higher octane gas wasnt "better" than 87 I dont think it would cost 30-40 cent more per gallon. The smell is even stronger and more concentrated when you pump it. But I am no expert, not by far. But I do know for a fact you dont have to have boost or supercharger or turbo to run 93 gas!!!!! 93 wasnt made specifically for performance cars!!!!!!! So dont even go there. My car ran good on 87 or 89 gas. No problems at all. But I notice a very big change in the car with 93. There is a CLEAR difference in how the car runs and behaves. And Im looking forward to finishing my engine mods so I can take full advantage.

I would check your timing if it really makes a night and day difference and see if it's advanced at all. I use 87 octane all day long, and so do many others. 87 octane is just as good as 110 octane gas. It's the usage of the gas that varies depending on what's required by the engine. He just explained the difference, not one being better than the other. I have friends who waste money on 93 octane gas, just to say they have to put 93 octane in.

The best way I can describe it is comparing 87 octane to 93 octane is apples to oranges.
Comparing 87 octane from mickeys to 87 octane from Valero, that's apples to apples. You can find a difference in quality or one being better than the other by going to a better supplier.

However, good luck with the engine modding, you should read into fuel types and needs a bit more though.

Admin Dude

You are equating quality with price based on the marketing hype. Higher octane fuel isn't "better" it's "different". The difference is in the rate at which it burns. Higher octane fuels just burn slower. Does your car need higher octane fuel? Perhaps, if you have increased the compression ratio, are boosted and are pushing the limits on the timing advance. An otherwise basic stock 5.0 should run great on 87 octane. If it doesn't, there is likely an underlying cause that needs to be addressed.

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This is just not true. Lower octane gas doesn't burn hotter, colder, faster or slower than high octane gas. 87 octane gas burns the same as does 93 octane gas from the same vendor. The only thing that changes burn characteristics from one pump gas fuel to the next is the mix formula for that fuel.

Chicago for instance, has a different fuel mix requirement than does say... Alaska, or Arkansas, etc.

The ONLY difference (taking into account octane rating as the only difference) is the fuel's ability to resist detonation on the compression stroke. Given the same chemical package as other fuels in the same region, even the flash point is the same (temperature required of an ignition source necessary to start combustion).

There are additional links toward the bottom of the page that will take you to related articles.

I see lots of sites all of the time (some of them seemingly legitimate) post phrases etc. indicating that the burn rate is slowed in higher octane fuels. So it's not just forums that propagate the myth but so-called, "Informational Reference Sites".

The rate that fuel burns has more to do with its specific gravity (the weight of the fuel) than anything else. Fuels with a specific gravity of at or near 70 will burn faster than fuels with a higher specific gravity rating.

All the higher octane additive does to the fuel is cause it to resist being detonated by compression.

Admin Dude

If higher octane gas wasnt "better" than 87 I dont think it would cost 30-40 cent more per gallon. The smell is even stronger and more concentrated when you pump it. But I am no expert, not by far. But I do know for a fact you dont have to have boost or supercharger or turbo to run 93 gas!!!!! 93 wasnt made specifically for performance cars!!!!!!! So dont even go there. My car ran good on 87 or 89 gas. No problems at all. But I notice a very big change in the car with 93. There is a CLEAR difference in how the car runs and behaves. And Im looking forward to finishing my engine mods so I can take full advantage.

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Higher octane gas is not "better". The fuel goes through an additional process that gives it an additive to resist detonation. The additive itself and the cost of the process is what makes it more expensive. The fuel base is the same as the base from the same refinery.

I've not idea what your mods are or what your final compression ratio might be. So over the internet, there's no way for me to say that this octane is better for your car than one. The easiest way to tell is to make a WOT throttle run, maybe even up an incline. If your car "knocks" then you need to either retard the timing or increase your octane. If it doesn't "knock" then putting a higher octane fuel into the tank isn't gaining you anything.

I have to assume that the car in question is the 94? 94 Mustangs don't have (to my knowledge) any knock sensors. So it's not like the timing will magically increase if you run a higher octane fuel.

Here's something else you can try though... The gas station you got your most recent fill at... Try their next lower grade of gas. Often, there are large differences in how well fuels run in a given car. There can be a big difference in fuel of the SAME octane rating from gas stations right next door to each other. It just depends on where their fuel comes from and the a refinery and additive mixture that is in it.

Here's the sucky part... Once you find a station that you like... Well.... lots of gas stations change supply vendors frequently. So don't be surprised if you find that the station you got a little more "zing" from, doesn't have the same feel the next time you fill up.

It will make a difference in an older engine with a ton of carbon build up.

Kurt

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Exactly I'm thinking that is what is happening Kurt.

I dont know the difference between 87 & 93 but there has to be one. Its clearly much more concentrated then 87. I felt like everyone else. "I'm using 87 till the wheels fall off." But I ran 93 for the first time in my life after about 24 cars and the car runs much better IMO. I'm not saying it gained any horses or performance. But It runs much smoother. When I said night and day I was really only talking about the pick up is much better and to me the trans shifts a little tighter. Minor stuff but to me it makes a major difference. That's all I was saying. maybe 93 doesnt burn slower it just burns better??????? I dont know. But on the weekends its 93 for me from now on.

Higher octane gas is not "better". The fuel goes through an additional process that gives it an additive to resist detonation. The additive itself and the cost of the process is what makes it more expensive. The fuel base is the same as the base from the same refinery.

I've not idea what your mods are or what your final compression ratio might be. So over the internet, there's no way for me to say that this octane is better for your car than one. The easiest way to tell is to make a WOT throttle run, maybe even up an incline. If your car "knocks" then you need to either retard the timing or increase your octane. If it doesn't "knock" then putting a higher octane fuel into the tank isn't gaining you anything.

I have to assume that the car in question is the 94? 94 Mustangs don't have (to my knowledge) any knock sensors. So it's not like the timing will magically increase if you run a higher octane fuel.

Here's something else you can try though... The gas station you got your most recent fill at... Try their next lower grade of gas. Often, there are large differences in how well fuels run in a given car. There can be a big difference in fuel of the SAME octane rating from gas stations right next door to each other. It just depends on where their fuel comes from and the a refinery and additive mixture that is in it.

Here's the sucky part... Once you find a station that you like... Well.... lots of gas stations change supply vendors frequently. So don't be surprised if you find that the station you got a little more "zing" from, doesn't have the same feel the next time you fill up.

Higher octane gas is not "better". The fuel goes through an additional process that gives it an additive to resist detonation. The additive itself and the cost of the process is what makes it more expensive. The fuel base is the same as the base from the same refinery.

I've not idea what your mods are or what your final compression ratio might be. So over the internet, there's no way for me to say that this octane is better for your car than one. The easiest way to tell is to make a WOT throttle run, maybe even up an incline. If your car "knocks" then you need to either retard the timing or increase your octane. If it doesn't "knock" then putting a higher octane fuel into the tank isn't gaining you anything.

I have to assume that the car in question is the 94? 94 Mustangs don't have (to my knowledge) any knock sensors. So it's not like the timing will magically increase if you run a higher octane fuel.

Here's something else you can try though... The gas station you got your most recent fill at... Try their next lower grade of gas. Often, there are large differences in how well fuels run in a given car. There can be a big difference in fuel of the SAME octane rating from gas stations right next door to each other. It just depends on where their fuel comes from and the a refinery and additive mixture that is in it.

Here's the sucky part... Once you find a station that you like... Well.... lots of gas stations change supply vendors frequently. So don't be surprised if you find that the station you got a little more "zing" from, doesn't have the same feel the next time you fill up.

Most purchase fuel from the least expensive supplier.

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Wouldnt that mean that the additives make 93 "better" than 87 or 89? Otherwise what would be any point of ever creating 93 or turbo blue etc etc? I am asking because I want to know.
The car is fully functional. Their are zero mechanical problems with this car. No pinging no lean no rich no nothing. It was running very well before I put the 93 in. But when I went 93 I felt a little extra pep in my step. I thought I had been missing out all this time. The car is a 94. And I really only get gas from Mobil especially 93. I dont like to whore around for gas because I had a bad experieince with my Bronco years ago going to Sunoco. As far as my Stang I ran 93 for a week straight. It ran well. I went back to 87 the next week. It seemd to me to go back to usual. then I went to 89... eh. Then back to 93. Pep clearly came back. Maybe it is what Kurt said all the old carbon and stuff cleaning out of there I dont know. I just thought I had been missing out on something all these years of driving.

Admin Dude

Wouldnt that mean that the additives make 93 "better" than 87 or 89? Otherwise what would be any point of ever creating 93 or turbo blue etc etc? I am asking because I want to know.
The car is fully functional. Their are zero mechanical problems with this car. No pinging no lean no rich no nothing. It was running very well before I put the 93 in. But when I went 93 I felt a little extra pep in my step. I thought I had been missing out all this time. The car is a 94. And I really only get gas from Mobil especially 93. I dont like to whore around for gas because I had a bad experieince with my Bronco years ago going to Sunoco. As far as my Stang I ran 93 for a week straight. It ran well. I went back to 87 the next week. It seemd to me to go back to usual. then I went to 89... eh. Then back to 93. Pep clearly came back. Maybe it is what Kurt said all the old carbon and stuff cleaning out of there I dont know. I just thought I had been missing out on something all these years of driving.

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That depends on what you mean by "better". Is 93 octane better for high compression and/or boosted applications? Hell yes.

Is it "better" for a relatively low combustion motor that doesn't ping at WOT on 87 octane gas? No.

Is it better for vehicles equipped with knock sensors and OBD2? Usually, but not always. It depends on whether that EEC was programed to sample and make use of a higher octane fuel. The later year Mustangs CAN and DO.

These days, the fuel additives for cleaning engines is pretty much the same across the board. That was not always the case. Many of those engine detergents are now mandated by law regardless of the octane rating of the fuel.

I googled and looked up a few things and what you all are saying seems to be true. There is no proven advantage to using 93 over 87. Like I said I dont know what it does. I have NEVER used 93 before this car. But I do know it made the car behave diffrently. But I'm thinking the extra little bit of "pep" is due to more what Kurt was saying as far as carbon build up. Shame shame shame on oil companies for calling it Regular, Super, Premium. Liars, robbers, and theives. SMH.

SN Certified Technician

Some quotes from your reference support the position that higher octane fuel doesn’t make the car run better. This was what the discussion was about.

“Consumers should select the lowest octane grade at which the car's engine runs without knocking. Occasional light knocking or pinging won't harm the engine, and doesn't indicate a need for higher octane. On the other hand, a heavy or persistent knock may result in engine damage.”

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And

“Are you tempted to buy a high-octane gasoline for your car because you want to improve its performance? If so, take note: the recommended gasoline for most cars is regular octane. In fact, in most cases, using a higher octane gasoline than your owner's manual recommends offers absolutely no benefit. It won't make your car perform better, go faster, get better mileage or run cleaner. Your best bet: listen to your owner's manual.”

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This quote supports the position that all brands aren’t the same.

“The quality of gasoline and the additive package usually affect the rate of engine wear more than the octane rating. Basically what this means is that it matters more where you buy your gas than which grade you purchase.”

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“The rate that fuel burns has more to do with its specific gravity (the weight of the fuel) than anything else. Fuels with a specific gravity of at or near 70 will burn faster than fuels with a higher specific gravity rating.”

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It is my understanding that these octane additives increase the specific gravity which results in a slower burn rate. The slower burn rate is what causes the gasoline to resist being detonated by compression. Is that not true?

Admin Dude

Some quotes from your reference support the position that higher octane fuel doesn’t make the car run better. This was what the discussion was about.

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True statement. Higher octane alone doesn't make a car run better that does not require it. It just costs more.

And

This quote supports the position that all brands aren’t the same.

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This is also true. Not all "brands" are the same. Brand selection is nearly impossible for the consumer to predict or anticipate. It's not listed like the ingredients on a cereal box as to what they did to the fuel to get it to meet the standards required in the region that it's sold.

It is my understanding that these octane additives increase the specific gravity which results in a slower burn rate. The slower burn rate is what causes the gasoline to resist being detonated by compression. Is that not true?

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The specific gravity of fuel is largely effected by the additive/detergent package and not so much by the process that gives it its octane rating. The last time I looked really hard into it, Chicago was one of the worst for requiring the largest amount of "garbage" be put into their fuels package. Additives are added based on things like elevation, climate, smog impact, and even the amount of stop and go traffic vs. long haul (catalyzation additives). All of those 'other' things that go into a package have a much larger effect on the specific gravity of a fuel.

This is why it's a lot more likely to feel a difference between fuels with the same octane rating but are from different vendors than it is on fuel based on octane alone.

What's more is that there aren't a lot of station that sell a specific brand of fuel to begin with. Some that do (I would think anyway, I've not verified), would be places like Shell, Exxon, and maybe BP. Many of the places that we all get gas from aren't so brand specific. They sell gas to get you into their stores where the real money is made.

Sunoco seems to be one of the companies that concentrate more on performance. There are probably 50 different ways to meet the package requirements for a region. They at least tout that they spend the extra time to find a package that meets the requirements and performs as best as they can make it (race fuels aside, that's a different story all together).

Every notice how in different parts of the country you see water coming from the tail pipes of cars a lot more than others? That's the additive package talking. You usually see more of this in places that have colder climates. Even if it's currently summer time.

Seafoam gets the crap out of your intake. I don't think it does anything for the stuff that's built up inside the cylinders. If you have a ton of carbon deposit on the piston top and around the valves it can cause hot spots that cause portions of the fuel to burn too fast resulting in loss of performance. If enough of the fuel is burning too fast it will cause the stereotypical pinging. Higher octane fuel is more stable and less likely to burn too fast. So he probably just got to the point where more of the fuel was burning evenly resulting in the extra pep.

Admin Dude

I've seen some stuff (I can't remember what it was called) that comes in a can that you connect to your fuel rails.

You hang it from the open hood like an IV bag and run the car from it until it's empty and the car dies. That stuff, is supposed to be good at cleaning combustion chamber deposits. Maybe someone will come along that knows what it is.